The research outlined in this proposal centers on the investigation of the biologically relevant system properties of lipid bilayers formed from purified glycosphingolipids, and systems comprised of well characterized phospholipids containing variable amounts of cholesterol and glycosphingolipids of the types found in mammalian cell plasma membranes. Studies will also be undertaken on reconstituted membranes comprised of plasma membrane lipids and purified glycoproteins derived from these membranes or appropriate viral membranes. Attention is focused primarily on differences in concentrations and types of glycosphingolipids and glycoproteins similar to those differences described between normal and oncogenically transformed cells. The work outlined will utilize three systems, liposome dispersions, planar bilayers and monolayers formed at an air/water interface. Liposomes will be used to study both compositional asymmetry between opposite bilayer faces and compositional domains within the planes of the bilayer. Studies of bilayer permeability and structure as functions of composition and temperature will be undertaken in systems exhibiting compositional domains. Details of the interactions between lipids will be examined directly using monolayer techniques. The proposed studies will depend upon a variety of physical techniques including the use of fluorescent probes, NMR spectroscopy (H, 13C and 31P), scanning calorimetry, partial molal volume measurement and the use of hydrodynamic methods to characterize liposome dispersions.